anyone out there on wells?? just bought 7 acres with 3 well,s.getting plenty of water,but get a little sand at times?? wuz-up?

-- al-d (dogs@zianet.com), May 06, 2000

Answers

Q-Why didn't the girl drink beer at the beach party?

A-She didn't want to get sand in her Schlitz

-- (Bluto@animal.house), May 07, 2000.

-- al-d,

During a three year break I took from the power industry I owned a small pump shop selling and servicing pumps for rural locations. We often had enquiries from people with similar problems to what you describe. There are a number of possible causes, and unfortunately you are probably not going to like any of them.

The most basic cause is that your well is caving in at the bottom due to:

a) The casing has corroded away allowing free sand to ingress to the intake area. Solution - Vaccuum out the sand in the bottom and replace the well lining, or drill a new well with new casing alonside the old well.

b) The well is unlined in the intake area, (quite common in hard or gravelly soils), but the water offtake exceeds the soil stability and has resulted in subsidence in the lower well section. Solution - Vaccuum out the sand, and Re-drill the lower section of the well, and either line it with perforated tube, or fit a smaller pump with a reduced flow.

A less likely cause is that your pumping system uses a sand filter that has not been correctly maintained, and all that is need is to replace the filter.

In either of the situations where the sand is actually coming from the well, there is a cheap (and nasty) soulution that will work for a while. Raise the pump intake to midway between the sand floor of the well and the water surface: Fit a very fine screen on the intake imediately below the foot valve, and: Wind up the pressure switch setting so that the pump switches itself off at a higher pressure. (Higher pressure means a lower water flow) This will give you cleaner water, but its harder on the pump, and doesn't really cure the cause of the problem.

I have two wells on my own property, and I never want to back to chlorinated, flourinated and chemically tasting town water again.

-- Malcolm Taylor (taylorm@es.co.nz), May 07, 2000.

thank you malcolm,much appreciation.

-- al-d (dogs@zianet.com), May 07, 2000.

If you just have A LITTLE sand at times, the main problem is to keep it out of the plumbing. Buy a sand filter for whole house use. It has a clear enclosure and a cleanable mesh insert. Sand will collect at the bottom and adding a ball drain there makes blowing the sand into a bucket easy. Has worked for many years in my house!

-- WFK (goodwater@home.now), May 07, 2000.

al-d, you have been a-peeking! I posted the same question at Countryside (twice). Our situation is 1/2 h.p. pump was doing fine in sandy soil. Then we got the bright idea to put on a full 1 h.p., sand soon followed. Clogged the washer. Well digger says, "yes, your well is going dry, you need another $1,500.00 to $3,000.00 well dug. But enough generous internet people were willing to offer alternative possibilities that I have held off on borrowing the money to sink a new well. Call it "hoping for a miracle". Well "hope" is still free. Malcolm, can you offer any suggestions? P.S., we have zilch experience in this area, so anything you know, is more than we know. Thanking you in advance.

-- My story and I'm (sticking@toit.com), May 07, 2000.

My Story,

Yes, I can understand that going from a 1/2 HP to a 1 HP pump would cause the symptoms that you describe. "Going dry" isn't quite the correct description of what is happening to your well, but the final effect is about the same.

What happens in the bottom of the well is that as you draw water out of the hole that has been drilled, water will gradually seep back in to replace it. If your well is 1 ft in diameter, and it is drilled to a depth of 20 ft below the water table, then it has a surface area of 62 square ft. Your 1/2 HP pump may extract 5 gallons (imperial) per minute, or 1/2 cubic ft of water per minute, so that the speed of water flowing into the well through the soil is only 1/124 ft/minute or 1/10 of an inch per minute. This is pretty slow and most soils would handle that degree of movement without any problem. But once you decided to double the pump size, you also increased the speed that the water must travel through the soil, and as the water moves faster it carries fine particles with it. Gradually your well starts to subside, filling in the bottom and giving sand into your water. As this process continues, the surface area of the well decreases, and speeds up the degradation untill at some point the well will fail.

The solution is to clean out the well if possible and go back to the smaller pump. In the part of New Zealand where I worked on pumps the cost of cleaning a well was between $2500 and $4000 depending on the depth, and a new well was between $7000 and $10000.

If you really want to use a 1 HP pump, then you need a deeper well, and hence a larger surface area. I don't know what the geology of your area is, or how deep the water table is, but the prices that you have been quoted do seem reasonable.

-- Malcolm Taylor (taylorm@es.co.nz), May 08, 2000.